Detonation tubes are simple devices capable of producing substantial acoustic power that may be useful for the simulation of high-level acoustic environments. We report results of an investigation into the modification of the acoustic spectrum produced by detonation tubes by timed addition of the shock- wave outputs of six detonation tubes fired in sequence. We first examined the output of a single detonation tube as a function of range and found that it conformed to existing models for spherical blast waves when appropriate initial conditions were derived. We found timing schemes for the firing of the multiple tubes that: (1) produce a substantial shift of the acoustic energy to lower frequencies by maximizing the duration of the positive pressure pulse, or (2) maximize the acoustic energy output in a narrow frequency range by matching the pulse-to-pulse delay to the total duration (positive and negative pressure phases) of a single detonation wave.